A number of major cruise lines have made their onboard smoking policies more restrictive.

Cunard Line, Disney Cruise Line, MSC Cruises, P & O Cruises, Royal Caribbean International and Seabourn all announced changes recently. Depending on the line and the ship, the new policies will affect guest balconies, staterooms and public spaces.

Douglas Ward, author of the guidebook “Berlitz Cruising and Cruise Ships 2014,” said that the changes are “simply evolutionary — more no-smoking passengers are asking the cruise lines to reduce the smoking areas.”

Traditionally, most ships had smoking and smoke-free areas, he said. “Ocean liners of yesteryear were famous for their large smoking rooms.”

Many of the new policies prohibit smoking on balconies.

“Smoking on balconies causes a lot of upsets,” Ward said. “I receive numerous letters from passengers who do not want to smell the smoke of their balcony neighbors.”

Colleen McDaniel, managing editor of the website Cruise Critic, said the topic of smoking on balconies always results in heated discussions among cruisers. “So we’re not too surprised to see lines re-evaluating their policies,” she said. Disney announced its fleetwide balcony smoking ban last month; it will take effect Nov. 15.

Smoking has never been allowed in guest staterooms, a Disney spokeswoman said, but “portions of open-air decks on each ship are designated as smoking areas in an effort to provide a cruise experience that satisfies both our nonsmoking and smoking guests.”